1. Technical Field
The present invention relates to a steering column, and more particularly, to a steering column capable of minimizing a deviation in operating force of a control lever by a telescope operation.
2. Description of the Related Art
Generally, a steering column is an apparatus which is formed to enclose a steering shaft transferring rotational force generated by operating a steering wheel by a driver to a rack-pinion mechanism to support a rotation of the steering shaft and is coupled with a vehicle body through a bracket to fix a position of the steering shaft.
The steering column may further include a telescope function or a tilt function for convenience of a driver, in which the tilt is to control a fixed angle of the steering wheel and the telescope has two hollow tubes inserted thereinto so as to be able to be expanded and contracted in an axial direction and has a function of absorbing impact energy while the steering shaft and the steering column collapsing at the time of a collision of a vehicle.
Therefore, the steering column may be divided into a telescope type or a tilt type according to the foregoing function. In some cases, the tilt function may be added to the telescope type steering column and a driver may smoothly operate the steering wheel by controlling protrusions or a tilt angle of the steering wheel suiting a driver's height or body type using the foregoing functions.
As such, the telescope or tilt operation of the steering column is generally performed by allowing an outer tube to press or press-release an inner tube depending on a tightening operation and a tightening releasing operation of the control lever.
Further, for the outer tube to press the inner tube, the outer tube is provided with a slit in a lengthwise direction thereof, in which one end of the slit is opened and the other end thereof is closed.
However, the steering column according to the related art has a problem in that deformations of the outer tube are different due to the slit of which the one end is opened and the other end thereof is closed to cause a deviation in fixing force.
In detail, as the rigidity of the outer tube is minimal when the control lever is operated (tele-out) at the opened end of the slit, the deformation of the outer tube is maximal, but as the rigidity of the outer tube is maximal when the control lever is operated (tele-in) at the closed end of the slit, the deformation of the outer tube is minimal, such that the deviation in the fixing force occurs.
To improve the foregoing problem, the steering column of Korean Patent Laid-Open Publication No. 2011-0096805 (hereinafter, referred to as ‘related art’) is proposed and a schematic configuration of the steering column will be described with reference to FIG. 1.
As illustrated in FIG. 1, the steering column according to the related art is provided with a hollow-shaped inner tube 50 enclosing a steering shaft 75 and an outer tube 10 formed in a hollow shape into which the inner tube 50 is inserted and provided with telescope guides 35 which are opposite to each other in a lengthwise direction, protruding to an outer circumferential surface thereof to be provided with a control lever (not illustrated), in which the outer circumferential surface between the telescope guides 35 is provided with a first slit 20 cut in a direction of the steering shaft 75 and the outer circumferential surfaces of both ends of the telescope guides 35 each are provided with second slits 25 cut in a circumferential direction.
In this configuration, the second slits 25 are installed at both sides in a circumferential direction at portions of both ends of the first slit 20.
Therefore, the deviation in fixing force of the outer tube 10 is minimal at tele-in and tele-out positions by the second slit 25.
However, the steering column according to the related art has a problem in that to minimize the deviation in fixing force, the second slits need to be additionally machined and thus the a machining effort is increased to cause an increase in manufacturing costs.
Therefore, there is a need to develop a steering column overcoming the foregoing problems.